Microorganisms
- Insects infest. Microorganisms infect. An organism of microscopic size.
Bacteria, the tree pathogens, may be as small as 3 microns wide by 5 microns
long. A micron is a thousandth of a millimeter, which is a thousandth of a
meter, which is about 39 inches. A microscope is required to see bacteria.
Fungi are also microorganisms. Their microscopic cells are often joined to
form long tubes. As small as some fungi are, their fruit bodies may be very
large. Some perennial, hard "woody" fruit bodies of some fungi weigh over 20
pounds. Hardly a microorganism! Other microorganisms that inhabit trees are
viruses, mycoplasmas, slime molds, and protozoa. We know very little about the
blue-green algae that are in the size range of bacteria. The blue-green algae
have been found in fungus fruit bodies. This is important because some
blue-green algae can fix nitrogen from the air into nitrates. Other small
organisms that live in, on, and about trees are the microscopic roundworms, the
nematodes, and the amoebae. Blue-green algae are really cyanobacteria.
Picture on left is a fungus with its fruiting body.